How to determine total vapour pressure of solution in liquid phase as well as gas phase ?

According to Raoult's Law: The partial pressure of any volatile component of a solution at any temperature is equal to the vapour pressure of the pure component multiplied by the mole fraction of that component in the solution.

      Where X_A­ and X_B is the mole fraction of the component A and B in liquid phase respectively

According to Dalton's Law:

The vapour behaves like an ideal gas, then according to Dalton's law of partial pressures, the total pressure P_Tis given by:

 Partial pressure of the gas = Total pressure x Mole fraction

                                        P_A = P_T Y_A and P_B =P_T Y_B

Where Y_A­ and Y_B is the mole fraction of the component A and B in gas phase respectively

Combination of Raoult's and Dalton's Law:

(3) Thus, in case of ideal solution the vapour phase is phase is richer with more volatile component i.e., the one having relatively greater vapour pressure

Graph Between 1/YA Vs 1/XA:

According to Dalton's law of partial pressures, the total pressure P_T is given by:

 Partial pressure of the gas = Total pressure x Mole fraction

Where Y_A­ and Y_B is the mole fraction of the component A and B in gas phase respectively

According to Raoult's law:

On rearrangement of this equation we get a straight line equation:

Illustrative Examples:

Liquid A and B form ideal solution at temperature T. Mole fraction of A in liquid and vapour phase are 0.4 and 4/13 respectively, when total pressure is 130 torr. The vapour pressure (in torr) of A and B in pure state at temperature T are respectively.

Solubility of gases and Henry's Law:

When a solution containing w of urea in 1kg of water is cooled to 272K, 200g of ice is separated. If for water is 1.86Kkgmol−1,w is:

Related Questions;

(1) An aqueous solution has 5% urea and 10% glucose by weight. what will be the freezing point of this solution ? ( Kf = 1.86 K Kg per mole)

(2) Acetic acid dimerised to an extent of 30% in benzene . The observed molecular mass (in gm) is...

(3) How much ice will separate if a solution containing 25 g of ethylene glycol [C2H4(OH) 2] in 100g of water is cooled to 10°C? Kf(H2O) = 1.86 (25.05 g)

(4) The dielectric con stant of H2O is 80. The electrostatic force of attraction between Na+ and Cl–will be.

(5) The van't Hoff's factor for 0.1 M Ba(NO3)2 solution is 2.74. the degree of dissociation is.

(6) Aqueous solution of 0.004 M Na2SO4 and 0.01 M glucose are iosotonic .The degree of dissociation of Na2SO4 is ..

(7) How can derivatives relation between relative lovering of vapour pressure and molality?

(8) A saturared solution of XCl3 has a vapour pressure 17.20 mm Hg at 20°C, while pure water vapour pressure is 17.25 mm Hg. Solubility product (Ksp) of XCl3 at 20°C is

(9) Calculate the percentage degree of dissociation of an electrolyte XY2 ( normal molar mass=165) in water if the observed molar mass by measuring elevation in boiling point is 65.5.

(10) Which of the following pair of solution (aq.) contain isotonic solution at same temperature? (Assume 100 % ionisation of electrolytes) (1) 0.1 M NaCI and 0.2 M CaCI2(2) 0.1 M NaCI and 0.3 M AICI3 (3) 0.3 M NaCI and 0.1 M AICI3 (4) 0.3 M NaCI and 0.2 CaCI2

What is Azeotropic mixture or solution?

A solution which boils like a pure liquid and has same composition in liquid as well as vapour phase is called Azeotropic solution or mixture.

Features of Azeotropic mixture:

# For Azeotropic solution XA =YA

# An ideal solution can not form Azeotropic mixture.

# only non ideal solution form Azeotropic mixture.

# composition of Azeotrope alter on changing external pressure.

# Azeotropic solution can't separated by fractional distillation.

Type of Azeotropic solution or mixture:

(1) Minimum boiling Azeotropic solution. 

It is formed by solution which show positive (+) deviation from ideal behaviour. Such solution has boiling point smaller than boiling point of both of components liquids.

For example, mixture of 95% ethanol by weight and 4% of water. 

Water boils at 373 K, and ethanol boils at about 351.5K, while azeotropes mixture of both boil at around 351.15 K, suggesting a boiling point lower than its constituents.

(2) Maximum boiling Azeotropic solution.

It is formed by solution which show negative (-) deviation from ideal behaviour. Such solution has boiling point larger than boiling point of both of components liquids.

For example,  mixture of approximately 20% by weight hydrochloric acid and 79 % of water.

Water boils at 373 K and hydrochloric acid boil at about 188 K,  while azeotropes  of both boil at around 383 K which is a boiling point greater than its constituents.

Related Questions;

(1) An aqueous solution has 5% urea and 10% glucose by weight. what will be the freezing point of this solution ? ( Kf = 1.86 K Kg per mole)

(2) Acetic acid dimerised to an extent of 30% in benzene . The observed molecular mass (in gm) is...

(3) How much ice will separate if a solution containing 25 g of ethylene glycol [C2H4(OH) 2] in 100g of water is cooled to 10°C? Kf(H2O) = 1.86 (25.05 g)

(4) The dielectric con stant of H2O is 80. The electrostatic force of attraction between Na+ and Cl–will be.

(5) The van't Hoff's factor for 0.1 M Ba(NO3)2 solution is 2.74. the degree of dissociation is.

(6) Aqueous solution of 0.004 M Na2SO4 and 0.01 M glucose are iosotonic .The degree of dissociation of Na2SO4 is ..

(7) How can derivatives relation between relative lovering of vapour pressure and molality?

(8) A saturared solution of XCl3 has a vapour pressure 17.20 mm Hg at 20°C, while pure water vapour pressure is 17.25 mm Hg. Solubility product (Ksp) of XCl3 at 20°C is

(9) Calculate the percentage degree of dissociation of an electrolyte XY2 ( normal molar mass=165) in water if the observed molar mass by measuring elevation in boiling point is 65.5.

(10) Which of the following pair of solution (aq.) contain isotonic solution at same temperature? (Assume 100 % ionisation of electrolytes) (1) 0.1 M NaCI and 0.2 M CaCI2(2) 0.1 M NaCI and 0.3 M AICI3 (3) 0.3 M NaCI and 0.1 M AICI3 (4) 0.3 M NaCI and 0.2 CaCI2

(11) Freezing point of pure liquid A is T K. If some amount of non-electrolyte non-volatile impurity is added in A, an ideal solution is formed. On cooling at 200 K, only 30% (by mass) liquid A is present and at 201 K, 60 % (by mass) liquid A is present. The value of T is .

(12) Liquid A and B form ideal solution at temperature T. Mole fraction of A in liquid and vapour phase are 0.4 and 4/13 respectively, when total pressure is 130 torr. The vapour pressure (in torr) of A and B in pure state at temperature T are respectively.

(13) 2 millimolar solution of sodium ferrocyanide is 60% dissociated at 27°C. osmotic pressure of the slotution is .

(14) Decimolar solution of K4[Fe(CN)6] dissociate by 60% at 27°C. Determine osmotlc pressure in Nature/M2.

(15) A complex is represented as CoCl3.xNH3.Freezing point of its 0.1 molar solution is - 0.558° C (Kf = 18.6) Assuming 100 % dissociation and coordination number of Co(iii) is six , the what is the complex formula ?

(16) A complex is wrltten as M(en)y.xBr. lts 0.05 molar solution shows 2.46 atm osmotlc pressure at 27°C. Assuming 100 % ionisaton and coordination number of metal (iii) is six, complex may be:

(17) Find the freezing point of a solution when 5 moI of Kl is mixed with 1 moI of HgCI2 in 3500 g of H20. Kf of H20 1.86 K/m. (KI + HgCI2 --> K2Hgl4 + KCI)

(18) A mixture of weighing 228 g contain CaCl2 and NaCl . If this mixture is dissolved in 10 kg of water and form ideal solution that boil at 100.364 ℃ The mol % of NaCl in mixture is [ kb of water = 0.52 K per mol Kg]

(19) What is the Raoult's law and it's application ?

(20) What is Vapour pressure of liquid ?

50 ml of dry ammonia gas was sparked for a long time in an eudiometer tube over mercury. After sparkling, the volume becomes 97 ml. After washing the gas with water and drying, the volume becomes 94 ml. This was mixed with 60.5 ml of oxygen and the mixture was burnt. After the completion of the combustion of H2 , the volume of residual gas was 48.75 ml. Derive the molecular formula of ammonia. (Given, N and H are only present in ammonia molecule).

Related Questions:

(1) 1 ml of gaseous aliphatic compound CnH3nOm is completely burnt in an excess of O2 and cooled to room temperature. The contraction in volume is..

(2) 1 ml of gaseous aliphatic compound CxHyOz is completely burnt in an excess of O2 and cooled to room temperature. The contraction in volume is..

(3) 50 ml of C3H8 is mixed with 300 ml of oxygen for complete combustion find out the final volume and volume concentration.

(4) 10 ml of gaseous hydrocarbon on combustion gives 40 ml. of CO2 (g) and 50 ml of H2O (vap). The hydrocarbon is